PROJECT SUMMARY The long-term goal of this proposed project is to develop an innovative, end-user informed Delivery of Antiretrovirals via Implantable System for Young children (DAISY). DAISY will offer a combination of product attributes that surpass existing oral regimens for antiretroviral treatment (ART) in young children (ages 2-5): long-term ART (at least 6 months), reversibility during drug delivery, user independence, biodegradation, and discretion of use. With a focus on preferred user characteristics in the Republic of South Africa (RSA), the DAISY platform aims to extend time between clinic visits and simplify dosing regimens of antiretrovirals (ARVs) in young children to ultimately improve adherence, and thus, viral suppression, disease progression, and childhood development. The implant is uniquely retrievable, if needed, for the duration of ARV delivery, but otherwise remains stationary and biodegrades after depletion of the drug. In this manner, reversal of drug delivery is possible in the case of adverse reactions or need to change in the regimen. The implant technology also decouples drug delivery characteristics from biodegradation properties and can achieve zero-order kinetics of ARV release. The proposed specific aims directly address the goals of this National Institutes of Health opportunity (RFA-AI-18-057) for innovative long-acting drug delivery systems for treatment of HIV-1 infected children. The specific aims are to (1) develop the DAISY product, including ARV formulations, implant form factors, and characterization of biodegradation; (2) evaluate safety, pharmacokinetics, and efficacy of down-selected DAISY prototypes during preclinical studies in New Zealand White rabbits and nonhuman primates; and (3) inform technology development via iterative socio-behavior research with end-user populations in RSA. Importantly, the proposed work will leverage achievements made during earlier programs in developing the implant platform and will build on this work in the following key aspects: long-term delivery (up to 6 months) of multiple ARVs and incorporation of end-user acceptability data from RSA into a Target Product Profile. Our Research Strategy is milestone-driven, with clear expected deliverables guiding progress of product development to align with future clinical translation.